International Law: Rulebook or Rhetoric?

Let's imagine a world where every pilot decided which side of the sky to fly the plane, or every merchant ship had to fight its way through every coastline it passed. It would be a disaster, expensive and probably wouldn't last long or unsustainable. This is the platform upon which International Law performs, a delicate balancing act where 193 sovereign actors try to follow the same script without a single director to enforce it. In essence countries cooperate and follow rules voluntarily. There is no global government to boss them around. The big question is whether International law a rulebook that works, or just fancy talk from the powerful? Does it keep order or is it just high-sounding rhetoric used by strong nations?